Hi again! I am just sourcing the rear axel assembly for my F27 project. I know that any sierra (except estate) will be fine. So its only a question of ratio, and brake type.

What ratio is ideal, which should be steered clear of, and which should be satisfactory?

I have the choice between disc brake set up or drums. Cost is king on this project for both build, and once it is finished and used for track days. I am thinking of going for the drum option as is 60quid cheaper, plus (I believe) cheaper to replace parts, plus the handbrake is easier to use? Obviously aesthetics is another question!...either way, any advice would be much appreciated!

Thanks is advance.
Matt

Does the F27 use the horrendous beam axle mechanism from the Sierra? If not, then you can also use an estate as the diff is the same on all the Sierras.

If it (F27) does use the whole system then I'll shut up!


Oh, and the ratio you want will depend on what engine and what gearbox ratios you intend to use.

Cheers,
James

[Edited on 9/6/10 by James]

Drum braked rear:
Push in driveshafts with tripodes
Drum brakes (you knew that) but can use standard brackets to add disks
Lighter weight hub bearing carrier (good)
Lighterweight driveshafts
Tripode joints more messy to split (you have to cut up the beanz can bits)


Disk braked:
Bolt on driveshafts with CV joints
Disk brakes as standard (that don't fit under 13inch wheels)
Heavier bearings carrier
Some diffs are LSD (no LSD's used push in shafts)


Go drums if you want lightweight and aren't a slave to the bling of rear disks.

Matt

re: diff ratio

what engine are you using ?
what gearbox are you using ?
what size tyres will you have ?
do you want it to be screeming its head off at 70mph in top gear or something a bit more relaxed ?



as for the brakes I think you've kind of answered your own question
and as above the added bonus of drums is the weigh and you can get a conversion kit if you want discs later

the only downside of the rear drums is you won't be able to just swap the diff for a ford LSD one - atleast not without custom shafts
(the ford LSD's only come with 'bolt-on' driveshafts)
aftermarket LSD's will fit either kind though

[Edited on 9/6/2010 by mcerd1]

Awsome thanks for the replies.

Vauxhall 8v engine with fireblade carbs.
Type 9 five speed gearbox.
Planning on putting 15" wheels with 40 or 45 profile tyre. (One place for a slight compromise on aesthetics!)


I dont think the engine will be leggy enough to be doing much on long straights on circuits - I'd imagine that the car will be more fun on smaller tighter circuits. Deffinitly not looking for a relaxed drive as it will be a track only car.

Double wish bone set up on the rear.

Just found out the guy who has the rear axels I have been looking at only has discs available. One with a 3.62 ratio, and the other with 3.92. £170 all in.

What do ya think? Cheers again.

£170 for a rear axle a few years back I got 2 whole cars for less than £60 the pair (no MOT's)


if its a doulble wishbone rear then why can't you use the estate bits ? or even granada/scorpio bits ?
I know some chassis can't use the larger 7.5" diff, but these were fitted on all kinds of sierra's and granada's not just estates




also download this and have a play with the ratio's / tyre sizes: http://locost7.info/gearcalc.php
just bear in mind the top speeds quotes assume your engine has unlimited power
better to look at the bit that gives you revs in each gear/speed and make your mind up from that

[Edited on 9/6/2010 by mcerd1]

Not sure about the estate bit either I used one.. No different from the others???

Didto getting a whole car, seems lots running around still in london so they are out there...

Dan

I have got a coswoth rear axle you can have for 150 quid
3.62 7" LSD
driveshafts
hub carriers
rear beam
vented discs but no calipers

This would be awsome!! I will U2U you now!
Thanks a million!

where abouts in the country are you ?


btw - I've got some recon solid disc type calipers for sale at the moment - no carriers and the won't fit the cossie hubs - but the normal hubs they fit will work with the cossie 4x4 shafts/diff
(in other words you can mix and match a bit to end up with an XR4x4 spec rear axle instead of a cossie 4x4 one)

[Edited on 9/6/2010 by mcerd1]

Based in Brackley (down the road from Northampton) not quite next door to where you are! Not passing this way anytime soon are you?!?

Its a good point though - I need to be sure I can get the right calipers...

quote:

---

Originally posted by mcg
not quite next door to where you are!

---

Done! Thanks for the info.

These calipers seem very decent. So these, plus the parts that madteg have offered (plus new pads) should be all I need I assume?

Does anyone think that cossie calipers and vented discs is a little overkill for the rear end of this car given the modest power that I will be getting from it, plus the minimal proportion of braking the rears do anyhow...The big plus for this set up is of course the LSD!....hmmmm...